怎样以下SQL语句转为LINQ查询？该如何解决

怎样以下SQL语句转为LINQ查询？
自己转换了一个，但是得不到期望的结果...
SQL语句：

SQL code

select top 5    authorName,count(*)from dbo.authorsgroup by authorNamehaving authorName like '赵%'order by   count(*) desc 

C# code

  V1DataContext DB = new V1DataContext();                    var queryName = (from A in DB.authors                                     group A by new                                     {                                         authorName = A.authorName                                     } into grA                                     select new                                     {                                         authorName = grA.Key.authorName,                                         Quantity = grA.Count()                                     } into orderbygrA                                     where  orderbygrA.authorName.StartsWith("张")                                     orderby orderbygrA.Quantity descending                                     select orderbygrA.authorName).Distinct().Take(7);

C# code

var query=(from A in DB.authors.Where(b=>b.authorName.StartsWith("张"))          group A by A.authorName into g          let c=g.Count()          orderby c desending          select new {authorName=g.Key,cnt=c}).Take(5);